1. Field of the Invention
The invention relates to an X-ray device which includes an X-ray imaging apparatus and an X-ray generator for powering an X-ray source which co-operates with the X-ray imaging apparatus and also includes a diaphragm unit which is connected to the X-ray source and includes an adjustable diaphragm aperture in order to preset an exposure field on an X-ray image detection device, the diaphragm aperture being adjustable on the one hand by a drive unit which is controlled by a control system and on the other hand by adjusting means for manual adjustment of the diaphragm aperture.
2. Description of the Related Art
X-ray devices of this kind are known for the formation of Bucky images. Such devices utilize image detection devices in the form of film/foil combinations of various formats which are accommodated in suitably dimensioned cassettes. The examiner then selects the cassette format required for the next X-ray exposure and inserts the cassette into the X-ray device. The X-ray device is provided with a measuring device for measuring the cassette format. The control system then adjusts the diaphragm aperture in dependence on the measured cassette format so that the exposure field corresponds to the cassette format or the format of the film present therein. Such X-ray devices require manual adjustment of the exposure field only if the examiner wishes to constrict the exposure field.
Since recently so-called "digital" X-ray detectors are used as the image detection devices; such detectors include a large number of (for example, 2000.times.2000) detector elements which are arranged in the form of a matrix, are sensitive to light or X-rays and generate electric signals which are dependent on the X-ray intensity and are processed in the X-ray device. The X-ray device may comprise various imaging units, for example a grid exposure table for forming X-ray images of a supine patient and/or a grid wall stand for forming X-ray images of a standing patient; each of these units is provided with only a single digital detector of this kind whose dimensions, therefore, have to correspond to the largest possible exposure format (for example, 43.times.43 cm). Automatic adjustment of the diaphragm aperture to the format of this image detector, however, would in most cases require a rather substantial manual restriction of the exposure field, thus complicating the use of such an apparatus.
Citation of a reference herein, or throughout this specification, is not to be construed as an admission that such reference is prior art to the Applicants' invention of the invention subsequently claimed.